| 摘要 |
PROBLEM TO BE SOLVED: To provide a double-acting type extrusion press which holds a predetermined stop position without moving in longitudinal direction at a bearing part of a die during extrusion, and has holding means of a mandrel which suppresses fluctuation of a tip end position of the mandrel and obtains a tubular shaped product.SOLUTION: Provided on a main cross head is a position determination means for regulating a forward going position of a mandrel so that when a predetermined amount of pressure oil is supplied into a rod side chamber of a piercer cylinder and the mandrel stops during extrusion of the supplied amount and when the extrusion stem goes forward, the forward position of the mandrel coincides with an increased amount of the rod side chamber volume of the piercer cylinder. |
